Currently the main way of communication about time change to Audacity is factor*100-100, and that -100 part is bothering me. This confused me, when I thought +100 pitch change is that higher pitch (I mean the semitone one), but ended up being scared with the result. Multiplicative factor is not something to add or subtract to. This also leads to oversights by developers, -99 to 3000 actually meaning 1/100 to 31, and I was really disappointed that I couldn't use the fifth power of two (powers of two are statue numbers for pitch change, very essential). There is a factor for speed change. Tempo change has that fraction thing instead, where bpm from x to y is read by people like me as time from y to x. Young kids won't probably know that high pitch is 1 semitone up, they don't know what is a semitone.